(HealthNewsDigest.com) - Skin cancer is by far the most common form of cancer in the United States, with more new cases each year than breast, prostate, lung and colon cancers combined. And the rate of newly diagnosed cases of the most deadly skin cancer, melanoma, has tripled over the last three decades. But many of the sunscreens on the market do not provide enough protection from the sun's damaging rays. Also, some of them contain chemicals that can also cause health problems in their own right.

According to the non-profit Environmental Working Group (EWG), which assessed the safety and effectiveness of more than 1,400 "SPF" (sun protection factor) products for its 2014 Guide to Sunscreens, only one in three sunscreens for sale on the shelves of American stores offer good skin protection and are free of ingredients with links to health issues. "That means two-thirds of the sunscreens in our analysis don't work well enough or contain ingredients that may be toxic," reports the group.

A big part of the problem is the lack of tougher rules from the U.S. Food & Drug Administration (FDA). "The FDA's first major set of sunscreen regulations, 36 years in the making, took effect in December 2012 and proved far too weak to transform the market," reports EWG. While the new rules did restrict some of the most egregious claims on sunscreen labels (such as the "patently false" ‘waterproof' and ‘sweatproof' claims) and ended the sale of powder sunscreens and towelettes that were too thin to provide protection against ultraviolet rays, they didn't address inhalation threats from spray sunscreens or take into account the risks of exposure to so-called "nanoparticles" from zinc oxide and titanium dioxide varieties.

While the FDA is currently reassessing its stance on sunscreens, EWG warns it may be a while before new rules address these and other concerns, especially given push-back from regulatory-averse members of Congress and some manufacturers. So what's a health-conscious sun worshipper to do about sunscreen?

For starters, read labels. Some common sunscreen ingredients to watch out for and avoid include: oxybenzone, which can cause allergic reactions and hormone-like effects; Vitamin A (AKA retinyl palmitate), a skin irritant and possible carcinogen; and fragrances which can contain allergens and chemicals. Also, spray sunscreens are suspect because inhaling some of the ingredients can irritate breathing passages and even potentially compromise lung function. And EWG warns to avoid products with SPF ratings higher than 50, as their use can tempt people to apply too little and/or stay in the sun too long. Sticking with products in the 15-50 SPF range and reapplying often makes much more sense.

Some of the best choices are those sunscreens that employ either zinc oxide or avobenzone, both which have been shown to block the most damaging ultraviolet rays effectively without the need for other potentially troublesome additives. Some of the leading brands that meet EWG's criteria for both safety and effectiveness include Absolutely Natural, Aubrey Organics, California Baby, Elemental Herbs, Goddess Garden, Tropical Sands and True Natural, among others. Find these and other winners on the shelves of natural foods retailers as well as online. For a complete list of all 172 recommended sunscreens and to learn more about the risks, check out EWG's free online 2014 Guide to Sunscreens.